DENVER (AP) — The question of what should be considered too stoned to drive is being revisited by Colorado lawmakers.

Lawmakers are revisiting a bill that’s failed three previous times that would set a drivers’ blood standard for THC, the psychoactive ingredient in marijuana. The Transportation Legislation Review committee is expected to vote Friday on whether to introduce the bill in January.

The proposal would limit drivers to 5 nanograms of THC per milliliter of blood. Nevada and Ohio have a 2 nanogram THC limit for driving.

Republican Sen. Steve King says he’s bringing the bill forward again because public safety is at stake. But opponents worry medical marijuana users will be wrongly convicted of driving under the influence.